// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "tools/gn/scope.h"

#include "base/logging.h"
#include "base/stl_util.h"
#include "tools/gn/parse_tree.h"
#include "tools/gn/template.h"

namespace {

// FLags set in the mode_flags_ of a scope. If a bit is set, it applies
// recursively to all dependent scopes.
const unsigned kProcessingBuildConfigFlag = 1;
const unsigned kProcessingImportFlag = 2;

// Returns true if this variable name should be considered private. Private
// values start with an underscore, and are not imported from "gni" files
// when processing an import.
bool IsPrivateVar(const base::StringPiece& name) {
  return name.empty() || name[0] == '_';
}

}  // namespace


Scope::ProgrammaticProvider::~ProgrammaticProvider() {
  scope_->RemoveProvider(this);
}

Scope::Scope(const Settings* settings)
    : const_containing_(nullptr),
      mutable_containing_(nullptr),
      settings_(settings),
      mode_flags_(0),
      item_collector_(nullptr) {
}

Scope::Scope(Scope* parent)
    : const_containing_(nullptr),
      mutable_containing_(parent),
      settings_(parent->settings()),
      mode_flags_(0),
      item_collector_(nullptr) {
}

Scope::Scope(const Scope* parent)
    : const_containing_(parent),
      mutable_containing_(nullptr),
      settings_(parent->settings()),
      mode_flags_(0),
      item_collector_(nullptr) {
}

Scope::~Scope() {
  STLDeleteContainerPairSecondPointers(target_defaults_.begin(),
                                       target_defaults_.end());
}

const Value* Scope::GetValue(const base::StringPiece& ident,
                             bool counts_as_used) {
  // First check for programatically-provided values.
  for (const auto& provider : programmatic_providers_) {
    const Value* v = provider->GetProgrammaticValue(ident);
    if (v)
      return v;
  }

  RecordMap::iterator found = values_.find(ident);
  if (found != values_.end()) {
    if (counts_as_used)
      found->second.used = true;
    return &found->second.value;
  }

  // Search in the parent scope.
  if (const_containing_)
    return const_containing_->GetValue(ident);
  if (mutable_containing_)
    return mutable_containing_->GetValue(ident, counts_as_used);
  return nullptr;
}

Value* Scope::GetMutableValue(const base::StringPiece& ident,
                              bool counts_as_used) {
  // Don't do programatic values, which are not mutable.
  RecordMap::iterator found = values_.find(ident);
  if (found != values_.end()) {
    if (counts_as_used)
      found->second.used = true;
    return &found->second.value;
  }

  // Search in the parent mutable scope, but not const one.
  if (mutable_containing_)
    return mutable_containing_->GetMutableValue(ident, counts_as_used);
  return nullptr;
}

Value* Scope::GetValueForcedToCurrentScope(const base::StringPiece& ident,
                                           const ParseNode* set_node) {
  RecordMap::iterator found = values_.find(ident);
  if (found != values_.end())
    return &found->second.value;  // Already have in the current scope.

  // Search in the parent scope.
  if (containing()) {
    const Value* in_containing = containing()->GetValue(ident);
    if (in_containing) {
      // Promote to current scope.
      return SetValue(ident, *in_containing, set_node);
    }
  }
  return nullptr;
}

const Value* Scope::GetValue(const base::StringPiece& ident) const {
  RecordMap::const_iterator found = values_.find(ident);
  if (found != values_.end())
    return &found->second.value;
  if (containing())
    return containing()->GetValue(ident);
  return nullptr;
}

Value* Scope::SetValue(const base::StringPiece& ident,
                       const Value& v,
                       const ParseNode* set_node) {
  Record& r = values_[ident];  // Clears any existing value.
  r.value = v;
  r.value.set_origin(set_node);
  return &r.value;
}

void Scope::RemoveIdentifier(const base::StringPiece& ident) {
  RecordMap::iterator found = values_.find(ident);
  if (found != values_.end())
    values_.erase(found);
}

void Scope::RemovePrivateIdentifiers() {
  // Do it in two phases to avoid mutating while iterating. Our hash map is
  // currently backed by several different vendor-specific implementations and
  // I'm not sure if all of them support mutating while iterating. Since this
  // is not perf-critical, do the safe thing.
  std::vector<base::StringPiece> to_remove;
  for (const auto& cur : values_) {
    if (IsPrivateVar(cur.first))
      to_remove.push_back(cur.first);
  }

  for (const auto& cur : to_remove)
    values_.erase(cur);
}

bool Scope::AddTemplate(const std::string& name, const Template* templ) {
  if (GetTemplate(name))
    return false;
  templates_[name] = templ;
  return true;
}

const Template* Scope::GetTemplate(const std::string& name) const {
  TemplateMap::const_iterator found = templates_.find(name);
  if (found != templates_.end())
    return found->second.get();
  if (containing())
    return containing()->GetTemplate(name);
  return nullptr;
}

void Scope::MarkUsed(const base::StringPiece& ident) {
  RecordMap::iterator found = values_.find(ident);
  if (found == values_.end()) {
    NOTREACHED();
    return;
  }
  found->second.used = true;
}

void Scope::MarkUnused(const base::StringPiece& ident) {
  RecordMap::iterator found = values_.find(ident);
  if (found == values_.end()) {
    NOTREACHED();
    return;
  }
  found->second.used = false;
}

bool Scope::IsSetButUnused(const base::StringPiece& ident) const {
  RecordMap::const_iterator found = values_.find(ident);
  if (found != values_.end()) {
    if (!found->second.used) {
      return true;
    }
  }
  return false;
}

bool Scope::CheckForUnusedVars(Err* err) const {
  for (const auto& pair : values_) {
    if (!pair.second.used) {
      std::string help = "You set the variable \"" + pair.first.as_string() +
          "\" here and it was unused before it went\nout of scope.";

      const BinaryOpNode* binary = pair.second.value.origin()->AsBinaryOp();
      if (binary && binary->op().type() == Token::EQUAL) {
        // Make a nicer error message for normal var sets.
        *err = Err(binary->left()->GetRange(), "Assignment had no effect.",
                   help);
      } else {
        // This will happen for internally-generated variables.
        *err = Err(pair.second.value.origin(), "Assignment had no effect.",
                   help);
      }
      return false;
    }
  }
  return true;
}

void Scope::GetCurrentScopeValues(KeyValueMap* output) const {
  for (const auto& pair : values_)
    (*output)[pair.first] = pair.second.value;
}

bool Scope::NonRecursiveMergeTo(Scope* dest,
                                const MergeOptions& options,
                                const ParseNode* node_for_err,
                                const char* desc_for_err,
                                Err* err) const {
  // Values.
  for (const auto& pair : values_) {
    if (options.skip_private_vars && IsPrivateVar(pair.first))
      continue;  // Skip this private var.

    const Value& new_value = pair.second.value;
    if (!options.clobber_existing) {
      const Value* existing_value = dest->GetValue(pair.first);
      if (existing_value && new_value != *existing_value) {
        // Value present in both the source and the dest.
        std::string desc_string(desc_for_err);
        *err = Err(node_for_err, "Value collision.",
            "This " + desc_string + " contains \"" + pair.first.as_string() +
            "\"");
        err->AppendSubErr(Err(pair.second.value, "defined here.",
            "Which would clobber the one in your current scope"));
        err->AppendSubErr(Err(*existing_value, "defined here.",
            "Executing " + desc_string + " should not conflict with anything "
            "in the current\nscope unless the values are identical."));
        return false;
      }
    }
    dest->values_[pair.first] = pair.second;

    if (options.mark_used)
      dest->MarkUsed(pair.first);
  }

  // Target defaults are owning pointers.
  for (const auto& pair : target_defaults_) {
    if (!options.clobber_existing) {
      if (dest->GetTargetDefaults(pair.first)) {
        // TODO(brettw) it would be nice to know the origin of a
        // set_target_defaults so we can give locations for the colliding target
        // defaults.
        std::string desc_string(desc_for_err);
        *err = Err(node_for_err, "Target defaults collision.",
            "This " + desc_string + " contains target defaults for\n"
            "\"" + pair.first + "\" which would clobber one for the\n"
            "same target type in your current scope. It's unfortunate that I'm "
            "too stupid\nto tell you the location of where the target defaults "
            "were set. Usually\nthis happens in the BUILDCONFIG.gn file.");
        return false;
      }
    }

    // Be careful to delete any pointer we're about to clobber.
    Scope** dest_scope = &dest->target_defaults_[pair.first];
    if (*dest_scope)
      delete *dest_scope;
    *dest_scope = new Scope(settings_);
    pair.second->NonRecursiveMergeTo(*dest_scope, options, node_for_err,
                                     "<SHOULDN'T HAPPEN>", err);
  }

  // Sources assignment filter.
  if (sources_assignment_filter_) {
    if (!options.clobber_existing) {
      if (dest->GetSourcesAssignmentFilter()) {
        // Sources assignment filter present in both the source and the dest.
        std::string desc_string(desc_for_err);
        *err = Err(node_for_err, "Assignment filter collision.",
            "The " + desc_string + " contains a sources_assignment_filter "
            "which\nwould clobber the one in your current scope.");
        return false;
      }
    }
    dest->sources_assignment_filter_.reset(
        new PatternList(*sources_assignment_filter_));
  }

  // Templates.
  for (const auto& pair : templates_) {
    if (options.skip_private_vars && IsPrivateVar(pair.first))
      continue;  // Skip this private template.

    if (!options.clobber_existing) {
      const Template* existing_template = dest->GetTemplate(pair.first);
      // Since templates are refcounted, we can check if it's the same one by
      // comparing pointers.
      if (existing_template && pair.second.get() != existing_template) {
        // Rule present in both the source and the dest, and they're not the
        // same one.
        std::string desc_string(desc_for_err);
        *err = Err(node_for_err, "Template collision.",
            "This " + desc_string + " contains a template \"" +
            pair.first + "\"");
        err->AppendSubErr(Err(pair.second->GetDefinitionRange(),
            "defined here.",
            "Which would clobber the one in your current scope"));
        err->AppendSubErr(Err(existing_template->GetDefinitionRange(),
            "defined here.",
            "Executing " + desc_string + " should not conflict with anything "
            "in the current\nscope."));
        return false;
      }
    }

    // Be careful to delete any pointer we're about to clobber.
    dest->templates_[pair.first] = pair.second;
  }

  return true;
}

scoped_ptr<Scope> Scope::MakeClosure() const {
  scoped_ptr<Scope> result;
  if (const_containing_) {
    // We reached the top of the mutable scope stack. The result scope just
    // references the const scope (which will never change).
    result.reset(new Scope(const_containing_));
  } else if (mutable_containing_) {
    // There are more nested mutable scopes. Recursively go up the stack to
    // get the closure.
    result = mutable_containing_->MakeClosure();
  } else {
    // This is a standalone scope, just copy it.
    result.reset(new Scope(settings_));
  }

  // Want to clobber since we've flattened some nested scopes, and our parent
  // scope may have a duplicate value set.
  MergeOptions options;
  options.clobber_existing = true;

  // Add in our variables and we're done.
  Err err;
  NonRecursiveMergeTo(result.get(), options, nullptr, "<SHOULDN'T HAPPEN>",
                      &err);
  DCHECK(!err.has_error());
  return result.Pass();
}

Scope* Scope::MakeTargetDefaults(const std::string& target_type) {
  if (GetTargetDefaults(target_type))
    return nullptr;

  Scope** dest = &target_defaults_[target_type];
  if (*dest) {
    NOTREACHED();  // Already set.
    return *dest;
  }
  *dest = new Scope(settings_);
  return *dest;
}

const Scope* Scope::GetTargetDefaults(const std::string& target_type) const {
  NamedScopeMap::const_iterator found = target_defaults_.find(target_type);
  if (found != target_defaults_.end())
    return found->second;
  if (containing())
    return containing()->GetTargetDefaults(target_type);
  return nullptr;
}

const PatternList* Scope::GetSourcesAssignmentFilter() const {
  if (sources_assignment_filter_)
    return sources_assignment_filter_.get();
  if (containing())
    return containing()->GetSourcesAssignmentFilter();
  return nullptr;
}

void Scope::SetProcessingBuildConfig() {
  DCHECK((mode_flags_ & kProcessingBuildConfigFlag) == 0);
  mode_flags_ |= kProcessingBuildConfigFlag;
}

void Scope::ClearProcessingBuildConfig() {
  DCHECK(mode_flags_ & kProcessingBuildConfigFlag);
  mode_flags_ &= ~(kProcessingBuildConfigFlag);
}

bool Scope::IsProcessingBuildConfig() const {
  if (mode_flags_ & kProcessingBuildConfigFlag)
    return true;
  if (containing())
    return containing()->IsProcessingBuildConfig();
  return false;
}

void Scope::SetProcessingImport() {
  DCHECK((mode_flags_ & kProcessingImportFlag) == 0);
  mode_flags_ |= kProcessingImportFlag;
}

void Scope::ClearProcessingImport() {
  DCHECK(mode_flags_ & kProcessingImportFlag);
  mode_flags_ &= ~(kProcessingImportFlag);
}

bool Scope::IsProcessingImport() const {
  if (mode_flags_ & kProcessingImportFlag)
    return true;
  if (containing())
    return containing()->IsProcessingImport();
  return false;
}

const SourceDir& Scope::GetSourceDir() const {
  if (!source_dir_.is_null())
    return source_dir_;
  if (containing())
    return containing()->GetSourceDir();
  return source_dir_;
}

Scope::ItemVector* Scope::GetItemCollector() {
  if (item_collector_)
    return item_collector_;
  if (mutable_containing())
    return mutable_containing()->GetItemCollector();
  return nullptr;
}

void Scope::SetProperty(const void* key, void* value) {
  if (!value) {
    DCHECK(properties_.find(key) != properties_.end());
    properties_.erase(key);
  } else {
    properties_[key] = value;
  }
}

void* Scope::GetProperty(const void* key, const Scope** found_on_scope) const {
  PropertyMap::const_iterator found = properties_.find(key);
  if (found != properties_.end()) {
    if (found_on_scope)
      *found_on_scope = this;
    return found->second;
  }
  if (containing())
    return containing()->GetProperty(key, found_on_scope);
  return nullptr;
}

void Scope::AddProvider(ProgrammaticProvider* p) {
  programmatic_providers_.insert(p);
}

void Scope::RemoveProvider(ProgrammaticProvider* p) {
  DCHECK(programmatic_providers_.find(p) != programmatic_providers_.end());
  programmatic_providers_.erase(p);
}
